Esterification of carboxylic acids with organic halides in the presence of water

ABSTRACT

IN A PROCESS WHEREIN AN ORGANIC HALIDE IS REACTED WITH AN ORGANIC ACID TO OBTAIN THE CORRESPONDING ESTER, THE IMPROVEMENT TO INCREASE THE AMOUNT OF ESTER WHICH INVOLES CARRYING OUT THE REACTION IN THE PRESENCE OF WATER.

United States Patent ESTERIFICATION 0F CARBOXYLIC ACIDS WITH ORGANIC HALIDES IN THE PRESENCE OF WATER Russell G. Hay, Gibsonia, and John G. McNulty and William L. Walsh, Glenshaw, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa.

No Drawing. Continuation-impart of application Ser. N 0. 785,794, Dec. 20, 1968. This application July 25, 1969, Ser. No. 845,080

Int. Cl. C07c 67/00 U.S. Cl. 260-410.9 R 21 Claims ABSTRACT OF THE DISCLOSURE In a process wherein an organic halide is reacted With an organic acid to obtain the corresponding ester, the improvement to increase the amount of ester which involves carrying out the reaction in the presence of water.

This application is a continuation-in-part application of our application Ser. No. 785,794, filed Dec. 20, 1968, entitled Process For Producing Esters, now abandoned.

This invention relates to a process for preparing esters, particularly a process for reacting an organic halide with an organic acid to obtain the corresponding ester.

An organic halide can be made to react with an organic acid to obtain the corresponding ester and water, for example, as in Canadian Pat. No. 765,833 to William L. Walsh, but unfortunately, particularly to low temperatures, the reaction proceeds with difficulty and, many times, with undesirably small amounts of ester. We have found that the amount of ester produced in such reaction can be greatly increased by the mere expedient of carrying out the same in the presence of a relatively large amount of Water.

The first reactant that is employed herein includes monobasic organic acids as defined in said Canadian Pat. No. 765,833, such as saturated straight chain aliphatic monobasic organic acids, that is, carboxylic acids, having from two to 30 carbon atoms, preferably from two to 22 carbon atoms; saturated branched chain aliphatic monobasic acids having from two to 30 carbon atoms, preferably from two to 22 carbon atoms, aromatic monobasic acids, saturated cyclic monobasic acids and straight and branched monobasic olefinic acids having from three to 22 carbon atoms, preferably from six to 22 carbon atoms. The first reactant can also include dibasic organic acids such as aliphatic straight and branched chain dibasic acids having from four to 22 crbon atoms, preferably from four to 18 carbon atoms, straight and branched chain olefinic dibasic acids having from four to 22 carbon atoms, preferably from four to 18 carbon atoms, cyclic dibasic acids having from five to 22 carbon atoms, preferably from five to 18 carbon atoms, and aromatic dibasic acids having from eight to 32 carbon atoms, preferably from eight to 18 carbon atoms; and polybasic acids 3,634,474 Patented Jan. 11, 1972 having from four to 22 carbon atoms, preferably from four to 18 carbon atoms.

To react with the monobasic and dibasic acids defined above to produce the desired ester in accordance with the process defined and claimed herein there must be employed an organic halide selected from the group consisting of primary straight and branched chain alkyl halides having from one to 30 carbon atoms, preferably from one to 22 carbon atoms; secondary straight and branched chain alkyl halides having from one to 30 carbon atoms, preferably from one to 22 carbon atoms; primary cyclic halides having from four to 22 carbon atoms, preferably from four to 12 carbon atoms; secondary cyclic halides having from three to 22 carbon atoms, preferably from three to 12 carbon atoms, primary straight and branched chain olefinic halides having from three to 22 carbon atoms, preferably from six to 22 carbon atoms; and secondary straight and branched chain olefinic halides having from three to 22 carbon atoms, preferably from six to 22 carbon atoms. Specific examples of each of the monobasic organic acids and organic halides that can be used herein are set forth in said Canadian Pat. No. 765,- 833, referred to above. Examples of dibasic acids that can be employed include specific examples of aliphatic straight and branched dibasic acids, such as succinic acid, glutaric acid, adipic acid, pimelic acid, azelic acid, sebacic acid, suberic acid, methylsuccinic acid, dimethylsuccinic acid, methyladpic acid, etc.; specific examples of straight and branched olefinic dibasic acids,"such as maleic acid, fumaric acid, methylmaleic acid, dimethylmaleic acid, ethylmaleic acid methylfumaric acid, dimethylfumaric acid, chloromaleic acid, dichloromaleic acid, glutaconic acid, etc.; specific examples of cyclic dibasic acids, such as cyclohexane dicarboxylic acid, cyclopentane dicarboxylic acid, cyclododecane dicarboxylic acid, etc.; specific examples of aromatic dibasic acids, such as ortho-phthalic acid, nitrophthalic acid, tetrachlorophthalic acid, etc., and specific examples of polybasic acids, such as tricarballylic acid, aconitic acid, citric acid, etc. of the organic halides defined above, we prefer to employ alkyl halides, particularly primary alkyl halides. Of the alkyl halides, we prefer alkyl chlorides and alkyl bromides. Although we prefer to employ the organic acids and the organic halides in approximately stoichiometric amounts, the molar proportions thereof can vary from about 10:1 to about 1:10.

As noted, the amount of ester produced is considerably enhanced b carrying out the reaction in the presence of Water. The molar ratio of water to the organic halide reactant defined above can be from about 1:1 to about :1, but preferably is about 2:1 to about 40:1.

In carrying out the reaction, the reactants defined above and the water are merely brought together in any convenient manner. The temperature can be as low as about and as high as about 250 C., but preferably is about to about 200 C. At the low temperatures, the reaction proceeds slowly, while at the higher temperatures shorter reaction times are required and the production of alcohols corresponding to the organic halide and some olefins and a slight increase in ether are obtained. Pressures are not critical and any pressure is suitable, but in order to maintain water in the reaction zone, a pressure of at least about one hundred pounds per square inch aqueous layer and an organic layer. The latter was analyzed by gas liquid chromatography.

The following procedure describes Runs N0. 17, 18 and 19. Into a.300 milliliter glass pressure reactor there gauge is preferred and pressures up to about 1000 pounds 5 was introduced an organic halide, a dibasic acid and per square inch gauge can be used. The reaction time is water. The glass reactor was placed in a shielded cage similarly not critical and is dependent upon the other and the contents stirred by a magnetic stirrer. The convariables involved and on the amount of conversion detents of the glass reactor were raised to reaction temsired. In general, a reaction time of about one minute to perature and pressured 100 to 150 pounds per square about 40 hours, preferably from about 15 minutes to inch gauge. After holding the contents of the glass reabout three hours can be used. actor for a selected period of time under the above con- During the course of the reaction, an ester, hydrogen ditions, the glass reactor was permitted to cool to room halide, water and some alcohol, ether and olefin are protemperature, opened, and the contents were found to be duced. The ester can be recovered from the reaction prodpresent as two layers, an aqueous layer and an organic not in any convenient manner. For example, upon coollayer. The latter was analyzed by gas liquid chromaing, the reaction mixture resolves itself into an aqueous tography, layer and an organic layer. Depending on the density The data obtained using propionic, valeric and pelarof the organic product formed, the organic layer can be gonic acids as the organic acid components are set forth either the upper or lower layer. The two layers can be in Table I. Data from the runs using o-phthalic acid are separated from each other in any convenient manner. set forth in Table II. For example, by decantation. The organic layer will The uniqueness of the present process is apparent from contain the organic components and the same can be a study of the data. In each instance wherein water was separated from each other in any suitable manner, for added to the reaction system, the amount of ester was example, by distillation. The aqueous layer contains the greatly increased. As the temperature was increased, the water originally present, water that formed, unreacted amount of olefin and ether was slightly increased, but organic acid and hydrogen halide. It is believed that the fortuitously, the amount of alcohol was also increased. hydrogen halide complexes or in some manner attaches Since the alcohol obtained corresponds to the organic itself to the water. The complex exists as a liquid. The halide employed, this is advantageous, since such alcoaqueous layer can be discarded, if desired, but in a hols are commercially desirable. In fact, it would be compreferred embodiment, the hydrogen halide and unremerically attractive to convert the esters produced to the acted organic acid can be recovered by subjecting the corresponding alcohols by hydrolysis. To the extent that aqueous layer to distillation at low pressures, for examalcohols are so produced, the commercial attractiveness ple, 100 millimeters of mercury, to remove substantially of the present process is thereby enhanced. all of the uncomplexed water and organic acid overhead, The results obtained herein are completely unexpected. after which the complex is subjected to distillation at an In the present process an organic halide is being reacted elevated pressure, for example, 75 pounds per square With an organic acid to obtarn the correspondmg ester of inch gauge to remove substantially anhydrous hydrogen Such. reactan s-- one Skllled 1n the art would not expect halide overhea that the addition of water to such reaction system would The process defined herein can be further illustrated produce beneficial results, that is, increase the amount of The following procedure describes the first sixteen runs. i i i g f i fact i g ig Into an 1800 milliliter stirred tantulum autoclave there p y m 3,515.0 orgamc resu was introduced an organic halide an organic acid and in -lthough the reaction P Organic aclds Wlth orgamc t Th t t f th t 1 halides to produce esters 1n the presence of water is the f runs 6 con an s e au 0c ave l new procedure described and defined herein, it may be to reactlon temperature an pr essured to 3 out pointed out that instead of the organic acid, its anhydride 200 to about 300 pounds per square 1nch gaug Aflier can be charged to the reaction zone and the reaction holfllng f Contents of the l f for a Selected proceeds to give the same product, since the anhydride, in per1od of tlme under the above conditions, the autoclave the presence of Water, is converted to the corresponding Was Permitted C001 room temperature, p and organic acid in situ. In an important commercial operathe contents were found to be present as two layers, an tion, phthalic anhydride would preferably be used rather TABLE I Mols charged Product, weight percent Pro- Pelar- Octyl Hexyl Octyl Run l-broruol-bromopionio Valerie gonic Temp., Time, propivalerpelarl-hexl-oeta- Dioctyl No. hexane octane acid acid acid Water 0. hours onate ate gonate anol nol Octenes ether 0.6 3.0 None 170 2.0 2.9 None None None 0.5 2.5 5.0 170 2.0 37.1 6.0 1.2 1.4 0.5 2.5 10.0 170 2.0 63.5 3.7 2.0 2.4 0.5 2.5 15.0 170 2.0 73.9 6.0 1.1 2.7 0.3 1.5 None 6.0 0.8 None None None 0.5 2.5 10.0 140 4.0 57.9 3.6 0.4 0.9 0.3 1.5 None 120 6.0 0.2 None None None 0.5 2.5 10.0 120 6.0 18.6 1.1 0.5 None 0.5 1.5 10.0 2.0 00.1 5.4 1.4 2.0 0.5 1.5 12.5 170 2.0 60.2 9.7 1.4 1.4 0.5 2.0 30.0 2.0 64.8 19.5 5.0 3.8 0.5 2.0 30. 205 0.75 40.9 34.3 10.5 5.0 0.25 1.0 20.0 199.2 1.0 50.7 36.3 3.2 4.7 0. 25 1.0 20.0 185 1.0 61.5 24.0 2.7 6.7 0.3 1. 5 6.0 170 2. 0 None None None 0.5 2.5 10.0 170 2.0 3.9

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